A ball of relative density 0.8 falls into water from a height of 2m. Find the depth to which the ball will sink

When the ball is in air, the ball accelerates with a acceleration of gms^-2 through a distance of 2m.

In water due to buoyancy the net force acting on the body will be $\Rightarrow {\mathrm{F}}_{\mathrm{net} }\mathrm{ma}=\mathrm{\sigma Vg}-\mathrm{\rho Vg}$

$\Rightarrow \mathrm{a}=\mathrm{g}\left(\frac{\sigma }{\rho }-1\right)=\mathrm{g}\left(\frac{1}{0.8}-1\right)=\frac{\mathrm{g}}{4}$in upward direction.

So, $\mathrm{g}.2=\mathrm{a}.\mathrm{h}\Rightarrow \mathrm{h}=8\mathrm{m}\left(\because \mathrm{a}=\frac{\mathrm{g}}{4}\right)$